Notts County's supporters trust should never have given away its majority control in the club to the anonymous investors who now own it, according to the chief executive of Supporters Direct, the government-backed body which promotes fans' involvement in running football clubs.

In a strongly-worded criticism of the trust, Dave Boyle argued that the fans should have insisted on retaining a voice on the Notts County board after the summer takeover, which is now the subject of intense scrutiny over the financial affairs of those involved.

"We believe it was not right for Notts County that the trust gave its shares away to unnamed investors, without securing a continuing role for supporters in decision-making," Boyle said.

"The principles behind supporters trusts are that football clubs are community institutions which depend on fans' loyalty, and that clubs will benefit from fans owning shares and being represented on the board. The Notts County Supporters Trust's own objectives were to seek ownership in the club, which it had, and representation in its running, which it also had, so by giving those away, the trust went against its very reasons for existing."

Boyle wrote to the trust's board, expressing his opposition, in June, before the takeover by Qadbak Investments went ahead. The board replied by emphasising what it has throughout, that the takeover was a once-in-history opportunity for the struggling League Two club to be bought by investors who would introduce substantial money.

David Hindley, a former trust board member, said he remains "deeply concerned" about the "lack of transparency" at the club. "Supporters worked extremely hard to secure the future of the club when it was faced by possible liquidation, and the trust was committed to openness," he said. "Yet still we do not even know who our new owners are, important details like the source of the money have not been made public, and the trust has not retained any shares or representation in the club. That is not what the trust stood for."

The trust had played a key role in rescuing County from administration in 2003, accumulated a 60% stake, and had elected directors on the club's board. The proposal that the trust hand over its shares, for free, to the new owners, and that all trust representatives resign from the club's board, was ultimately approved in July by 93% of trust members.

The immediate arrival of apparently huge money, the appointment of Sven-Goran Eriksson as director of football and high-profile signings including the short-lived Meadow Lane stint of Sol Campbell, appeared to vindicate that decision for most fans. However, the revelation about the central involvement at the club of Russell King, and the continuing refusal to disclose who the club's actual owners are, has fuelled concern among some that the trust board failed to establish sufficient detail, and gave the club away too completely.

Before the vote took place in July, the trust's board did provide limited information to the members for a takeover the trust's chairman, Glenn Rolley, described as: "The opportunity which Notts County supporters have waited for all of our lives."

The proposed new owners were stated to be Munto Finance, who issued a statement describing themselves as: "The special purpose acquisition company of a Middle East backed investment fund based in Switzerland."

That fund was subsequently stated to be Qadbak. No details have been given about the source of the money in Qadbak, or the identity of the investors, except that they are "Middle Eastern and European families who wish to remain anonymous".

In answers to members' questions, the trust board and John Armstrong-Holmes, a trust-elected director who was the club's chairman, said Munto had "substantial" funds to invest, and that "a merchant bank" was supporting the investment. Specific details were not provided.

"Whilst it is not prudent to publish an amount," the board said in the emailed answers, "it is substantial, and the club has an irrevocable bank guarantee that Munto will invest at least this amount in the club over the next five years."

First London plc, an investment bank, was stated to be supporting Munto and it has since been confirmed it provided the guarantee.

The takeover proposals stated that Munto wanted "100%" control, and did not want to spend money buying the club in the first place. So the trust agreed to gift its 60% stake to Munto and the supporter-elected directors resigned from the club's board.

"I believe very important details were not provided then," Hindley said, "and the Football League should establish who the club's owners are, and ensure this is disclosed to fans, before the takeover is passed as 'fit and proper'."

Glenn Rolley, the trust's chairman now and before the takeover, said today he remains convinced that the takeover was "in the best interests of the club", because money "far beyond my expectations" was brought to it.

"As far as I know, there is solid money there," Rolley said. "I have every confidence that the people involved are decent, and people are entitled to remain anonymous. A bank guarantee for multi-millions of pounds is in place."

Discussing the trust's decision to give up all involvement in the club's decision-making, he added: "Representation on the board was never on the table."